1. Field of the Invention
This invention relates to covers for automotive vehicle components.
2. Description of Related Art
Access covers applied to automotive components such as differentials, transmissions, and engine crankcases have taken a variety of forms. Steel stampings have frequently been used for this purpose, as have iron or aluminum castings. The most commonly employed sealing systems with covers of this type are flat paper or cork gaskets or sealants such as silicone rubber. The present invention has particular application to the area of differential covers.
Sealing of steel differential covers to cast iron housings has presented several problems in the past. Where such sealing is accomplished by means of a viscous sealant such as silicone rubber interposed between the cover and the differential housing, the sealant is squeezed to a thin film and as such has very little bond strength. Attempts to solve this problem by applying the sealant in a thicker film have generally not been satisfactory because the film is subject to extrusion during pressure leak testing of the assembled housing.
The present invention includes the use of an internal sealing flange to provide superior sealing capability with gearcase covers of differing materials. A preferred embodiment comprises a cover of plastic sheet molding compound.
Plastic material has previously been used for engine oil pans. U.S. Pat. No. 4,423,707 discloses a stamped plastic oil pan for use with an internal combustion engine. This oil pan uses a sealing system comprised of a rubber gasket which is molded prior to being placed between the oil pan and the engine crankcase sealing surface. Finally, U.S. Pat. No. 4,301,775 discloses a system for fabricating a manifold for an internal combustion engine in which cast manifold halves are sealed by injecting sealant into exterior joints along opposed side faces.